The present invention consists in a contactless payment method and device using a rechargeable medium. The medium is typically a microcircuit card (“smart card”) which can be read and written without physical contact via a radio link, but the invention can be applied to all rewritable media which can be read and written without contact. Some smart cards which can be read and written using a radio link can also be read by contact (magnetically, optically or electrically) and so can also be read and written by contact readers, i.e. readers which require the card to be inserted into a machine.
The method of the invention is more particularly intended to be used in the field of travel tickets. It is described in relation to that field, but other fields are feasible, in particular automatic dispensing.
Travel tickets are generally on a single-use medium, for example paper tickets carrying a magnetic stripe, because their cost is low compared to the fare. The user discards the ticket when a predetermined journey or a predetermined number of journeys has been completed or when an expiry date has been reached. Those media are read by contact in a reader.
Payment methods using a contact reader have the disadvantage of a low throughput of users, because each user takes some time to stop in front of a gate, take the ticket out of a pocket or handbag, insert it into a machine and recover it. It is necessary to provide parallel gates to increase the throughput of users.
For several years now, public transport ticketing systems have been evolving from the use of conventional tickets towards the use of contactless smart cards. However, the cost of these contactless cards (several hundred times the cost of a paper ticket with magnetic stripe) limits their use to season tickets or rechargeable tickets (tickets that the user can “recharge” in an automatic machine accepting payment by banknotes, coins or credit card), to retain a ratio close to one percent between the cost of the ticket per journey and the fare. Consequently, conventional tickets continue to be used either for all users or at least for occasional users who purchase tickets valid for only one journey (“single-journey tickets”).
Contactless smart cards are currently being used as public transport tickets on an experimental basis in France (Paris and Marseille) and for real (Seoul, Hong Kong, Washington, etc.). The system is generally referred to as teleticketing. To carry out all the standard functions of a microcircuit card, such as writing, reading, authentication, etc., the card can communicate over a short distance (approximately ten centimeters) with a coupler provided with an antenna. It usually also receives the power needed for it to operate from the antenna. This type of remote communication is currently being standardized by ISO Standard 14443. There are also combined cards operating without contact for transport access transactions and with contact for personalization or recharging transactions using standard contact equipment.
The teleticketing system has a number of advantages over conventional paper or magnetic stripe tickets:                there is no need to insert the ticket into a slot and recover the ticket from the same slot or an outlet chute, which reduces the overall time of a transaction by eliminating the human action and reaction times, and the electronic transaction time is short (approximately 100 ms to 200 ms) compared to a magnetic stripe transaction (from 500 ms to 1 000 ms), these two features increasing the throughput at the control point, which leads to a reduction in the number of control points;        users retain the ticket in the hand (or handbag), which eliminates the risk of loss or theft of the ticket at the time of payment;        more data can be stored in the memory card than on a magnetic stripe ticket and operators can therefore add to their knowledge of how the transport network is used;        a teleticketing reader is less costly than a magnetic stripe reader (by a factor of approximately 5);        the reader requires less maintenance because there are no mechanical moving parts;        the scope for vandalism is limited;        the scope for differential fare structures is extended; and        other applications (electronic purse) are also possible.        
On the other hand, the cost of a contactless ticket is much higher than that of a magnetic stripe ticket (by a factor of at least 1000) and in practice incompatible with the fare for a single journey or the cost of a basic service which can be paid for using a ticket of this kind. It is not feasible to use a medium of this kind to pay for a single journey and then discard it.
The contactless smart card is therefore restricted to season tickets and rechargeable tickets. In the transport field, where occasional users represent approximately 20% of all passengers and account for approximately 40% of revenue (because single-journey tickets do not benefit from reduced fares), cheap media continue to be used for single-journey tickets, for example paper tickets with a magnetic stripe. This significantly reduces the benefit of teleticketing because the need for the two systems to co-exist increases installation and maintenance costs and limits throughput.
In the field of conventional ticket ing, the problem of the coexistence of two systems has been solved (in Asia in particular) by using plastics material magnetic stripe cards to the standard format for all types of tickets, instead of using plastics material cards for season rickets and rechargeable tickets and paper or card single-journey tickets. The cost of manufacturing each plastics material card is greater than that of a paper or card ticket, but very much less than the cost of a smart card. The cost problem is solved by recycling, which reduces the cost per journey. A magnetic stripe card inserted into a reader is retained by the reader when it has no further value. After checking its physical condition, its value is recharged by rewriting it magnetically, and it is then sold again. In this way it can be used several hundred times, which reduces the cost per journey and therefore avoids the need for two systems to co-exist.
A transport company has no difficulty in recovering the magnetic stripe cards because all users must in all cases insert their magnetic stripe card into a terminal which reads the magnetic stripe on the card, possibly writes data on it, and then unlocks a gate or a barrier if the card shows sufficient credit for a journey. The cycle of use of a magnetic stripe card in the case of centralized recycling in a metro network is as follows:                1—Passengers purchase their tickets (single-journey tickets, rechargeable tickets or time-period tickets, etc.) from an automatic dispenser or at a ticket office.        2—The ticket is inserted into the reader of a terminal which controls physical entry and exit of passengers.        3—At the exit, the ticket is returned to the user if, after processing, it still has some value (sufficient credit for one or more journeys or a sum of money), or if the expiry date has not been reached.        4—The ticket is retained by the exit terminal if it shows no value after processing (which applies to all single-journey tickets).        5—In the case of centralized recycling, the recovered tickets are taken to a sorting center. They are checked to see if they can be used again. Those which can be used again are sorted by category.        6—The sorted tickets are returned to ticket offices or automatic dispensers and are magnetically written with the appropriate value when they are issued.        
The above description is somewhat simplified. Rechargeable tickets can be processed differently. Users can recharge them for themselves at an automatic machine accepting payment by banknote, coin, or credit card. In this case they are neither retained nor recycled by the gate. Other variants are equally possible. The current trend is for decentralized recycling at each station. The tickets are sorted in each gate, which limits the circulation of the tickets but complicates the gates.
To summarize, well known in the art are: payment methods using low-cost media, read by contact in a reader, but with the problem of a low throughput of users; and payment methods using contactless media achieving a fast throughput of users but causing a problem in terms of the cost of the media which leads to their use being restricted to certain tickets so that two ticketing systems have to co-exist.